The gut

The gut

Many people who begin on The Paleo Way not only experience improvements in how they feel physically, but also how they feel mentally and emotionally. How is it that what and how you eat affects your thoughts and emotions?

Many people who begin on The Paleo Way not only experience improvements in how they feel physically, but also how they feel mentally and emotionally. How is it that what […]

The good old phrase “trust your gut” has a solid physiological background. In fact your guts – i.e gastrointestinal tract – contains more brain cells (neurons) than your brain does, so it makes good sense to take heed of your “gut feelings”!

Where do those feelings come from? Well, the gut has it’s very own nervous system, called the enteric nervous system (ENS). It communicates with your brain via your vagus nerve. The ENS – your gut brain – uses the same neurotransmitters (brain messenger chemicals) as your head brain. So much so in fact that about 95% of your serotonin – one of your happy, calm, ordered, “rest and digest” neurotransmitters – is found in your gut, rather than in your head.   When food is detected in the gut, serotonin is released into the gut to stimulate the muscular squeezing of the gut wall that helps move food along the intestines.

In the brain, serotonin is responsible for regulating mood, preventing aggressive and impulsive behaviours, and regulating sleep, appetite, feeding and body weight.

Alcohol depletes serotonin which is why alcohol fuelled nights can result in impulsive and or aggressive outbursts that may later be regretted once the serotonin kicks back in again!

Low serotonin is associated with increased incidence of depression, obsessive compulsive disorders (OCD), alcoholism and anxiety. A study in one of the world’s most romantic countries – Italy – has demonstrated that serotonin also reduces when people fall in love, accounting for the obsessive behaviours that result at such times! Next time you’re in love with someone and can’t stop texting them or thinking about them, you can let them know it’s because they’ve dropped your serotonin levels!

A key factor of the production and function of serotonin is the presence of certain strains of beneficial gut bugs, including some types of lactobacillus and bifidobacterium.

Did you know that your gut houses more than 100 trillion microbes? In fact there are more bugs (bacteria, yeasts, parasites, viruses) living in you and on you as there are human cells. You’re outnumbered 10:1.

That’s right. You are more bug than human! Without enough of these beneficial microbes in the gut, it appears that production or signaling of serotnin can be inhibited, resulting in “fight or flight” symptoms (sympathetic nervous system overdrive) i.e. stress, depression, anxiety, poor memory, sleeplessness, poor mental organization and more.

Due to the effects of gut bugs on mental health symptoms, this class of probiotics is now being referred to as psychobiotics, a fancy term for “a live organism that, when ingested in adequate amounts, produces a health benefit in patients suffering from psychiatric illness.”   This is one reason why anyone experiencing any of these mental health symptoms is wise to address what is going on with their gut flora in order to resolve the root causes of the symptoms. Of course there can be other causes as well, but disrupted gut flora, as more and more research is showing, is a significant contributing factor.

As Louie Pasteur – creator of beer – stated on his death bed, it’s not just about bugs – it’s all about the terrain. What does that mean? It mean the environment we provide your microbes, determines what kind of microbes you play host to. And this is where the paleo way is so fantastic. We know that diets high in sugars, starches and processed foods foster the growth of undesirable bugs, while foods that create a healthy gut because they are nutrients dense, low starch and unprocessed actually provide an attractive environment for beneficial gut bugs. By keeping your gut healthy and your gut bugs happy, we have a much greater chance of keeping both brains – head and gut – healthy and happy too.

So next time you are feeling out of sorts, rather than just thinking it’s all in your head, have a brothee and think about what’s going on in your gut. You may find the answer there.


Badawy, Abdulla (2000). “Serotonin: the stuff of romance”. The Biochemist: 15–17.

Biol Psychiatry. 2013 Nov 15;74(10):720-6. doi: 10.1016/j.biopsych.2013.05.001. Epub 2013 Jun 10. Psychobiotics: a novel class of psychotropic Dinan TG1, Stanton CCryan JF. http://www.ncbi.nlm.nih.gov/pubmed/23759244


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